A conventional air purifier is shown in FIG. 6 and comprises a housing 11, a high voltage generator 12 and a discharging needle 13. The copper discharging needle 13 of the prior art is shaped as a cone and is coupled to the high voltage generator so that the needle 13 can discharge negative ions to be spread or mixed in air when high voltage electricity is provided by the generator 12. Consequently, the discharged negative ions in the air are increased for combining with positive ions resulting in a purification of the air. However, conventional air purifiers include a number of drawbacks including:
1. The discharging needle made of copper is shaped as a cone which limits the negative ions dispersement and lowers the purifying effect;
2. The discharging needle is immovably fixed to the front side of the housing, thus the dispersing negative ions discharge from the needle depends on movement of indoor air which may not reach around a room in which the purifier is placed;
3. Conventional purifiers do not generally clean and filter the air in a room before the discharge of negative ions and additionally, they do not force the air mixed with the negative ions to move around having a low air circulation dispersement.